scholarly journals Alteration of Fractionation and Bioavailability of Arsenic (As) in Paddy Soil under Transition from Aerobic to Anaerobic Conditions

2021 ◽  
Vol 20 (1) ◽  
pp. 1-7
Author(s):  
Apichaya Duangthong ◽  
◽  
Seelawut Damrongsiri ◽  
Keyword(s):  
Organic Compounds ◽  
Laboratory Simulation ◽  
Soil Conditions ◽  
Tetraacetic Acid ◽  
Anaerobic Conditions ◽  
Simulation Experiments ◽  
Long Period ◽  
Mobile Fraction ◽  
The Impact ◽  
Anaerobic Environment

The impact of the change from aerobic to anaerobic immersed soil conditions on arsenic (As) fractionation (Tessier’s method) and its bioavailability (ethylene diamine tetraacetic acid extractable) were assessed. As-contaminated paddy soils were tested by laboratory simulation experiments. The samples were aerobic, with 35-49 mg/kg of As at low bioavailability (<2%). Most As was distributed in the stable fraction (77%), followed by As bound to ferric and manganese oxide (17%) and organic compounds (5%), while the mobile fraction (exchangeable and mildly acid-soluble) was limited (1%). After one month under anaerobic simulation, redox potential reduced to less than zero (-32 to -124 mV). The stable fraction of As decreased (-17%), while the mobile fraction increased (+16%) and As bioavailability also increased (+26% total As). Increase in the As mobile fraction was associated with freshly precipitated compounds. The As content in the soil altered from a stable fraction to an available fraction when confined in an anaerobic environment for a long period. Results indicated that agricultural methods which promoted anaerobic conditions in As-contaminated soil should be avoided.

The methodological approach for the determination of the pressure of artificial raindrops as a question of the theory of splash soil erosion

2020 ◽  
pp. 24-28
Author(s):  
Mihail Zver'kov
Keyword(s):  
Block Diagram ◽  
Methodological Approach ◽  
Control Measures ◽  
Soil Conditions ◽  
Effective Pressure ◽  
Long Distance ◽  
Splash Erosion ◽  
Rain Drops ◽  
Artificial Rain ◽  
The Impact

To the article the results of the theoretical and experimental researches are given on questions of estimates of the dynamic rate effect of raindrop impact on soil. The aim of this work was to analyze the current methods to determine the rate of artificial rain pressure on the soil for the assessment of splash erosion. There are the developed author’s method for calculation the pressure of artificial rain on the soil and the assessment of splash erosion. The study aims to the justification of evaluation methods and the obtaining of quantitative characteristics, prevention and elimination of accelerated (anthropogenic) erosion, the creation and the realization of the required erosion control measures. The paper considers the question of determining the pressure of artificial rain on the soil. At the moment of raindrops impact, there is the tension in the soil, which is called vertical effective pressure. It is noted that the impact of rain drops in the soil there are stresses called vertical effective pressure. The equation for calculation of vertical effective pressure is proposed in this study using the known spectrum of raindrops. Effective pressure was 1.4 Pa for the artificial rain by sprinkler machine «Fregat» and 5.9 Pa for long distance sprinkler DD-30. The article deals with a block diagram of the sequence for determining the effective pressure of rain drops on the soil. This diagram was created by the author’s method of calculation of the effective pressure of rain drops on the soil. The need for an integrated approach to the description of the artificial rain impact on the soil is noted. Various parameters characterizing drop erosion are considered. There are data about the mass of splashed soil in the irrigation of various irrigation machinery and installations. For example, the rate (mass) of splashed soil was 0.28…0.78 t/ha under irrigation sprinkler apparatus RACO 4260–55/701C in the conditions of the Ryazan region. The method allows examining the environmental impact of sprinkler techniques for analyzes of the pressure, caused by raindrops, on the soil. It can also be useful in determining the irrigation rate before the runoff for different types of sprinkler equipment and soil conditions.

Mechanism of inhibition of succinate oxidase by products of oxidation of o-dihydroxycoumarins

1980 ◽  
Vol 45 (2) ◽  
pp. 641-652
Author(s):  
Petr Zbořil
Keyword(s):  
Inhibitory Activity ◽  
Oxidase Activity ◽  
Enzyme Preparation ◽  
Inhibitory Effects ◽  
Anaerobic Conditions ◽  
Long Period ◽  
Mechanism Of Inhibition ◽  
Intermediary Product ◽  
Succinate Oxidase ◽  
By Products

Semiquinone is an intermediary product of the oxidation of daphnetin (7,8-dihydroxycoumarin) and esculetin (6,7-dihydroxycoumarin) by diphenol oxidase; its concentration rapidly decreases. When the oxidation is effected by ferricytochrome c, the concentration of the semiquinone remains practically constant for a long period. Similarly, the ability of the products of daphnetin oxidation by diphenol oxidase to inhibit succinate oxidase activity in mitochondrial fragments rapidly decreases with time; the decrease is considerably slower in the case of cytochrome c. The inhibitory activity of the product decreases with time also during esculetin oxidation by ferricyanide. This indicates that the inhibitory effects must be ascribed predominantly to the semiquinone, the quinone is less efficient. The inhibition of succinate oxidase or succinate dehydrogenase was strongly decreased when the enzyme preparation of Keilin and Hartree was incubated with esculetin and ferricyanide in the presence of KCN or under anaerobic conditions. This demonstrates that the reaction of the inhibitor with the enzyme either involves subsequent oxidations or that the inhibitor preferentially reacts with the oxidized form of the sensitive component of the respiratory chain. The second alternative is very little probable since there is no correlation between the degree of inhibition and the binding of the inhibitor to mitochondrial fragments.

scholarly journals Time Granularity Impact on Propagation of Disruptions in a System-of-Systems Simulation of Infrastructure and Business Networks

2021 ◽  
Vol 18 (8) ◽  
pp. 3922
Author(s):  
Mateusz Iwo Dubaniowski ◽  
Hans Rudolf Heinimann
Keyword(s):  
Recovery Time ◽  
System Of Systems ◽  
Future Research ◽  
Business Networks ◽  
Simulation Experiments ◽  
Huge Impact ◽  
High Level ◽  
Systems Simulation ◽  
Different Characteristics ◽  
The Impact

A system-of-systems (SoS) approach is often used for simulating disruptions to business and infrastructure system networks allowing for integration of several models into one simulation. However, the integration is frequently challenging as each system is designed individually with different characteristics, such as time granularity. Understanding the impact of time granularity on propagation of disruptions between businesses and infrastructure systems and finding the appropriate granularity for the SoS simulation remain as major challenges. To tackle these, we explore how time granularity, recovery time, and disruption size affect the propagation of disruptions between constituent systems of an SoS simulation. To address this issue, we developed a high level architecture (HLA) simulation of three networks and performed a series of simulation experiments. Our results revealed that time granularity and especially recovery time have huge impact on propagation of disruptions. Consequently, we developed a model for selecting an appropriate time granularity for an SoS simulation based on expected recovery time. Our simulation experiments show that time granularity should be less than 1.13 of expected recovery time. We identified some areas for future research centered around extending the experimental factors space.

scholarly journals Effect of Storage Conditions on Storability and Antioxidant Potential of Pears cv. ‘Conference’

Agriculture ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 545
Author(s):  
Grzegorz P. Łysiak ◽  
Krzysztof Rutkowski ◽  
Dorota Walkowiak-Tomczak
Keyword(s):  
Mass Loss ◽  
Strong Influence ◽  
Storage Conditions ◽  
Quality Parameters ◽  
Soluble Solids ◽  
Controlled Atmosphere ◽  
Postharvest Diseases ◽  
Market Prices ◽  
Long Period ◽  
The Impact

Late pear cultivars, such as ‘Conference’, can be stored for a long period if kept in good storage conditions. A three-year study (2011–2013) compared the impact of six-month storage using four technologies—normal atmosphere, normal atmosphere + 1-methylcyclopropene (1-MCP), controlled atmosphere, and controlled atmosphere + 1-MCP—on the quality parameters of ‘Conference’ pears, such as mass loss, firmness, total soluble solids, acidity, antioxidant capacity, and the incidence of diseases and disorders. Additionally, the study analysed different storage conditions in terms of profitability, based on the market prices for pears in the seasons during which the pears were stored. The storage conditions had a very strong influence on the fruit quality parameters, and were found to affect most visibly the mass loss and the incidence of postharvest diseases and disorders. The storage of ‘Conference’ pears for 180 days in normal atmosphere is not economically viable, even if the fruit is subjected to 1-MCP treatment; at the same time, it is profitable to store ‘Conference’ pears in controlled atmosphere for the same period, no matter whether 1-MCP was applied or not.

scholarly journals Mobility and Bioavailability of Metal(loid)s in a Fluvial System Affected by the Mining and Industrial Processing of Pb

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 167
Author(s):  
Unai Cortada ◽  
María Carmen Hidalgo ◽  
Julián Martínez ◽  
María José de la Torre
Keyword(s):  
Total Concentration ◽  
Rare Metal ◽  
Mining District ◽  
X Ray ◽  
Industrial Processing ◽  
Solids Concentration ◽  
Mobile Fraction ◽  
Type Water ◽  
The Impact

The abandoned mining district of Linares (South Spain) is marked with waste from the mining and the processing of metal ores that pose an environmental hazard to watercourses. A combined analysis of waste, sediments and water was carried out to analyse the impact of a smelter on Baños Creek. The composition of the facility waste was determined using X-ray diffractometry and scanning electron microscopy. The total contents of the metal(loid)s in the waters and sediments of the watercourse were analysed, and sequential metal(loid) extraction of solid samples was carried out. The facility wastes consisted mainly of secondary minerals, such as natropharmacosiderite and spertiniite, as well as rare metal salts, such as mopungite and NaPb2(CO3)2(OH). The leachates generated by these wastes were highly alkaline, with a pH of 10 and a total dissolved solids concentration of approximately 9 g L−1. This Na-bicarbonate-type water had an As concentration above 200 mg L−1 and elevated levels of Pb, Sb and Zn (5029 µg L−1, 841 µg L−1 and 525 µg L−1, respectively). This highly contaminated lixiviate had a significant effect on the chemical quality of the waters and the bioavailability of metal(loid)s in the creek sediments, especially in the headwaters. In this zone, the As, Pb, Sb and Zn concentrations in the most mobile fraction of the sediments reached 1035 mg kg−1, 261 mg kg−1, 45 mg kg−1 and 30 mg kg−1, respectively. By comparison, smelter slag and mining waste have a much lower impact on the waters and the mobile fraction of the sediments, while significantly increasing the total concentration of these potentially toxic elements in creek sediments.

scholarly journals Anaerobic Conditions Induce Expression of Polysaccharide Intercellular Adhesin in Staphylococcus aureus and Staphylococcus epidermidis

2001 ◽  
Vol 69 (6) ◽  
pp. 4079-4085 ◽  
Author(s):  
Sarah E. Cramton ◽  
Martina Ulrich ◽  
Friedrich Götz ◽  
Gerd Döring
Keyword(s):  
Staphylococcus Aureus ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Extracellular Polysaccharide ◽  
Growth Conditions ◽  
Anaerobic Conditions ◽  
Anaerobic Environment ◽  
Specific Mrna

ABSTRACT Products of the intercellular adhesion (ica) operon in Staphylococcus aureus and Staphylococcus epidermidis synthesize a linear β-1,6-linked glucosaminylglycan. This extracellular polysaccharide mediates bacterial cell-cell adhesion and is required for biofilm formation, which is thought to increase the virulence of both pathogens in association with prosthetic biomedical implants. The environmental signal(s) that triggers ica gene product and polysaccharide expression is unknown. Here we demonstrate that anaerobic in vitro growth conditions lead to increased polysaccharide expression in both S. aureus and S. epidermidis, although the regulation is less stringent inS. epidermidis. Anaerobiosis also dramatically stimulates ica-specific mRNA expression inica- and polysaccharide-positive strains of both S. aureus and S. epidermidis.These data suggest a mechanism whereby ica gene expression and polysaccharide production may act as a virulence factor in an anaerobic environment in vivo.

Quality of Life Following Stroke: A Qualitative Study Across 30 Years

2021 ◽  
Vol 6 (1) ◽  
pp. 151-162
Author(s):  
Steffany M. Chleboun ◽  
Kathryn Brady ◽  
Jennie Zelenak
Keyword(s):  
Quality Of Life ◽  
Grounded Theory ◽  
Qualitative Study ◽  
Family Support ◽  
Resilience Theory ◽  
Grounded Theory Methodology ◽  
Long Period ◽  
The Impact

Much of what we know about stroke is limited to the first 5 years postinjury; however, the effects of having a stroke remain several years, even decades, postinjury, and the impact this has on an individual's quality of life over a long period of time is not completely understood. Purpose The purpose of this study was to understand one woman's experience living with the effects of stroke over multiple decades postinjury and to explore factors that affected her quality of life during this time. Method Using Grounded Theory methodology, data were drawn from 28 years of journals kept by the participant and from semistructured family interviews. Results Four major interacting themes emerged from the data: family support, faith, personality, and journaling. Findings are discussed in the context of resilience theory.

The Min-Max Load Criteria as a Measure of Machining Fixture Performance

1994 ◽  
Vol 116 (4) ◽  
pp. 500-507 ◽  
Author(s):  
E. C. DeMeter
Keyword(s):  
Convex Hull ◽  
Linear Model ◽  
Model Validation ◽  
Contact Region ◽  
Extreme Points ◽  
Simulation Experiments ◽  
Machining Operations ◽  
The Impact ◽  
External Loads ◽  
The Continuum

Spherical-tipped locators and clamps are often used for the restraint of castings during machining. For structurally rigid castings, contact region deformation and micro-slippage are the predominant modes of workpiece displacement. In turn contact region deformation and micro-slippage are heavily influenced by contact region loading. This paper presents a linear model for predicting the impact of locator and clamp placement on workpiece displacement throughout a series of machining operations. It illustrates how the continuum of external loads exerted on a workpiece during machining can be bounded within a convex hull, and how the extreme points of this hull are used within the model. Finally it describes the simulation experiments which were used for model validation.

scholarly journals The influx rate of long-period comets in the Earth's neighborhood and their debris contribution to the interplanetary medium

2012 ◽  
Vol 10 (H16) ◽  
pp. 140-140
Author(s):  
Julio Angel Fernández
Keyword(s):  
Steady State ◽  
Interplanetary Medium ◽  
Interplanetary Dust ◽  
Large Contribution ◽  
Influx Rate ◽  
Long Period ◽  
Impact Rate ◽  
Total Magnitude ◽  
Dust Complex ◽  
The Impact

AbstractWe analyze the flux of new and evolved long-period comets (LPCs) reaching the Earth's neighborhood (perihelion distances q < 1.3 AU), their physical lifetimes, and their implications as regards to the amount of meteoritic matter that is being deposited in the near-Earth region. The flux of LPCs with q < 1.3 au is found to be of about 340 ± 40, brighter than absolute total magnitude 8.6 (radius R ~ 0.6 km) (Fernández and Sosa 2012). Bearing in mind that most of these comets disintegrate into meteoritic matter, this represents a large contribution to the interplanetary dust complex which requires an amount of matter of about 10 tons s−1 to keep it in steady state. These aspects, as well as the impact rate with Earth of meteoroids of LPC origin, will be discussed in this presentation.

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